Ah, it's that time of year again - delightful summer beverages sipped in lovely outdoor locations.

But along with those icy drinks comes the inevitable condensation on the glass followed quickly by a little puddle around its base. Each tasty sip adds another drip to the front of your blouse, on the knitting in your lap or the pages of your book.
It's a good thing these absorbent, little cotton coasters are so quick to make. Most of us already have the required scraps of cotton yarn sitting in the stash. I used remnants from the Potholder Swap.

As with potholders, you can use any crochet motif that strikes your fancy. Make two circles (or squares, or hexagons. . .) for each and join them with your choice of crochet border.
There are many patterns and tutorials for the simple circles that I made, but here's my formula. I alternated one round per color of two colors, then added a contrasting edging.
(Assume that when I write dc here the
first dc in each round is actually a ch3 )
Create a loop with the
yarn and work 12 single crochets into it.
Next round: 2dc into each
of the 12. (24 sts)
Next round: (2dc into first st, 1dc into next
st.) to end of round. (36 sts)
Next round: (2dc into first st, 1dc
into next 2 sts.) to end of round. (48 sts)
Next round:
(2dc into first st, 1dc into next 3 sts.) to end of round. (60
sts)
Etc. to the size you want.

I used a 3.5mm (E) crochet hook and Rowan 4 ply cotton yarn.
I may even stick one or two of these in my bag for those outdoor cafes that fail to provide a cocktail napkin with my mojito.
On Raverly